Hydraulic pump assembly



Mardi 3,v 197() K. A. PRELEsNlK 3,498,229

HYDRAULIC PUMP ASSEMBLY Filed Nov, 1, 1967 2 sheets-sheet 1 ZZ J/ f I z l, 24 a, Ffa. l. f *nl /f o a u INVENTOR.

El /a KENNETH PRELESNML /z- Eg; V

BY QW, M

- .l Mange): 3, 1970 K. A. PRELESNIK A3,493,239

HYDRAULIC PUMP ASSEMBLY Filed Nov. 1, 196'? 2 Sheets-Sheet 2 o V uw k 'Rl y a 3 It) 3 s Q g N /8 r t: N ya* w- Nh, :l s E* B95 vk V l Si u www mvENToR.

United States Patent 3,498,229 HYDRAULIC PUMP ASSEMBLY Kenneth A. Prelesnik, Grand Haven, Mich., assignor to Dake Corporation, Grand Haven, Mich., a corporation of yMichigan Filed Nov. 1, 1967, Ser. No. 679,676 Int. Cl. F04b 49/00, 1/14; F04d 15/02 U.S. Cl. 103-37 4 Claims ABSTRACT 0F THE DISCLOSURE This disclosure relates to a hydraulic pump in which a plurality of piston cylinders are circularly located. Pistons in the cylinders are driven by a rotating cam plate, and the pistons are helically grooved, whereby rotation of the pistons with respect to the piston cylinders will vary the output volume of the pump.

A linearly reciprocatable shaft actuates a circular gear ring which in turn engages a slotted collar on each gear ring. Each piston shaft has a protruding foot which slides in the slot of the slotted collar.v

The output volume of the pump can be varied by employing an element responsive to the output pressure of the pump, operably connected to the linearly reciprocatable shaft. A handle or knob can also be used to adjust the position of the shaft to Vary the output pump volume.

This invention relates to a hydraulic pump. In one of its aspects it relates to a means for controlling the output volume of a hydraulic pump whose piston cylinders are arranged about a circular locus, and the pistons in the cylinders are actuated by a rotary cam plate, wherein each piston shaft contains a lug or foot which slides in a slot of a collar, which when turned, will vary the output capacity of the pump.

Many piston-type hydraulic pumps employ helically grooved pistons to vary the output volume of the pump. Different means have been employed to rotate the pistons within the cylinders, and thereby vary the output of the pump.

For example, Beeh, 2,428,408, discloses a fuel pump in which a plurality of piston cylinders having helically grooved pistons are arranged about a circular locus. The piston shafts have attached thereto a ring shaped member containing teeth, which engage a circular gear ring which can be moved to adjust each piston. The ring shaped member reciprocates with the piston and thus, provides a large area of sliding engagement with the adjusting ring.

Mashinter, 2,636,439, discloses a pump similar to that of Beeh, except that the adjusting ring is bifurcated and receives an end of a plunger throttle yoke containing a slotted end, which embraces the at shank portion of a piston rod. As the piston reciprocates, the yoke slides on the shank of the piston shaft.

I have now discovered an improved adjustment means for a pump containing a plurality of piston cylinders located about a circular locus, wherein the shaft of at least one piston contains a lug or foot which slidably engages a piston encircling ring which in turn, is rotated by a circular adjusting ring.

By various aspects of this invention, one or more of the following, or other, objects can be obtained.

It is an object of this invention to provide an improved means for adjusting the output volume of a hydraulic pump having a plurality of cylinders arranged about a circular locus, whereby frictional forces on the piston shaft from the adjusting means are minimized without loss of adjustment sensitivity.

It is a further object of this invention to provide a hydraulic pump which can be adjusted to maintain a con- C ice stant output pressure, wherein sensitivity of the adjusting means is maintained.

The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a side elevational view of the novel pump assembly according to the invention;

FIG. 2 is an end view of the novel pump assembly shown in FIG. 1;

FIG. 3 is a sectional view taken along lines III-III of FIG. 2;

FIG. 4 is a sectional view taken along lines IV-IV of FIG. l;

FIG. 5 is a perspective view of a piston employed in the pump; and

FIG. 6 is a sectional view similar to FIG. 4 showing a second embodiment of the invention.

Referring now to FIGS. 1 and 2, a pump housing comprises a rear housing section 2, a central housing section 4 and a front section housing 6 which sections are fastened together through bolts 8 on circular flanges of rear housing 2 and front housing `6. The central housing 4 has a first extension 19 containing an adjusting knob 16 and a second extension 20 positioned along the line of extension 19.

Referring now specically to FIGS. 3 and 4, a central shaft 22 is supported by a bearing assembly ring 28 and bearings 30 at one end of housing 2 and is supported in core member 36 by bearing ring 32 and bearings 34 at the other end of the rod. An oil seal 26 is provided to prevent oil from leaking out of the interior of the pump around rod 22. Cam member 38 is attached through key 42 to shaft 22. A thrust bearing 40 containing rotatable bearing members permits relatively frictionless rotation of ,cam 38 with respect to the back portion of housing 2. A

second thrust bearing containing rotatable bearing members 44 attached to plate 46, forces cam followers 50 journalled in sockets 52 to reciprocate piston shafts 54 containing pistons 56. A relatively stationary plate 48 separates the second thrust bearing from cam follower 50. A spring retainer 56 acting through spring 64, which abuts against slotted gear 96, maintains piston shaft 54 biased against thrust bearing 48. Piston 56 has a helical groove 58 which cooperates with port 86 of piston sleeve 68 to vary the discharge volume in piston chamber 66, formed by end member 69, piston sleeve `68 and piston 56. An annular slot 62 is provided beneath piston head 56 and communicates with chamber 66 through longitudinal groove 60. The annular groove 58 fixes the cut-off stroke, and thus limits the pumping capacity of the piston. Screw members 24, having pin 90 engage a slot 89 in the piston sleeve 68 to retain the piston sleeve in xed position.

The fluid enters the pump through inlet and enters the piston cylinders through ports 82 in core 36, through annular groove 84 and through inlet ports 86 and 88. The fluid is exhausted from chamber 66 through outlet port 70 around ball valve 72, maintained in place by spring 74 against screw member 14. The fluid then can leave through outlet channel 76 and through outlet port 12. Alternately, exterior outlet ports can be provided in the end of each cylinder such as at 14.

Piston shaft 54 has rigidly attached thereto a pair of lugs or feet 92 which engage slotted gear members 96 through a slot 94. This mechanical linkage zbetween the reciprocating piston shaft and the stationary but rotatable ring 96 minimizes frictional forces on the piston shaft without sacricing sensitivity of adjustment. Gear member 96 in turn, intermeshes with a circular gear ring 98 which circumscribes all of the piston cylinders and engages each slotted gear member 96 (see FIG. 4). Gear ring 98 has a slotted cihannel 106 around a portion of the outer circumference and has slots 100 to engage pin 104 of reciprocatable control rod 102 which is positioned in the circumferential channel 106. Control rod 102 threadably engages control shaft 118 at 116. The control shaft is attached to handle 16 and rigidly fastened thereto through a fastening screw 120. Control rod 118 is held in the center body part byend cap 122 through suitable threaded screw 124. The positioning of the gear ring 98 exterior of the piston cylinders provides for simple construction of the pump and leaves the interior free for the pumping function. By this arrangement, exterior oil seals in the interior of the pump are not required.

The extent of reciprocation of control rod 102 is limited by a control rod spacer 110 suitably attached to control rod 102 through pin 116. The extent of reciprocation of end spacer 110 is limited by a motion limiting chamber 112, having an abutting shoulder 108 vat one end thereof, and an end cap 114 at the other end thereof.

In operation, When it is desirable to change the capacity of the pump, control knob 16 is merely rotated, whereby control rod`116 is caused to move upwardly or downwardly, thereby rotating circular ring 98, which in turn axially rotates the slotted gear members 96, which rotate pistons 56 by rotating feet 92.

In the alternate embodiment of the invention shown in FIG. 6, knob 16 and control shaft 118 are replaced by a pressure sensitive piston 130, which is attached to control rod 102. A spring 132 is positioned in chamber 112 to bias the `control rod upwardly. A valve 134 is employed lto actuate the control rod 102 through piston 130The valve 134 contains an inlet port 136, an outlet port 138 and a pilot cone 140 between the two ports. The pilot cone 140 is biased against seat 1-42 by spring 144. The force exerted by spring 144 can be adjusted by knob 146 which threadably engages spring retaining guide 148. The valve body threadably engages the spring retaining valve guide 148. The inlet port 136 is connected to the pump outlet.

In operation, when the pressure in the pump outlet builds up, the pressure will force pilot cone 136 to be unseated. Since outlet port 138 has a relatively small aperture compared with inlet port 136, pressure builds up against piston 130 to force control rod 102 downwardly, thereby reducing the pump output in a manner which has been hereinbefore described. Y

When the pump output pressure drops, the pilot cone will be forced against seat 142, thereby closing the valve. `As the pressure bleeds from the valve, spring 132 will force piston 130 and control rod 102 upwardly to increase the pump output in a manner which has been hereinbefore described.

It has been described how the manually adjustable pump of FIGS. 1-5 can be easily converted to a variable capacity pressure sensitive pump.

In still another embodiment of the invention, knob 16 can be replaced by a simple shaft or lever which can be pulled up or down to vary the capacity yof the pump.

I claim:

1. In a hydraulic pump assembly comprising:

a housing having a central cavity and forming a common outlet port;

a fluid inlet port in said housing communicating with said central cavity;

a plurality of piston chambers arranged around a circular locus in said housing, each piston chamber having an inlet port communicating with said central cavity and an outlet port communicating with said common outlet port;

a piston in each piston chamber for pumping fluid entering each piston chamber through said chamber inlet port out through said chamber outlet port;

each piston having at one end thereof a helical groove which cooperates with said'inlet port in said piston chamber to close off the piston chamber to said chamber inlet port and pump fluid out said chamber outlet port;

check valve means in said chamber outlet port to permit exhausting of fluid under pressure through said chamber outlet port, and to prevent llow of iiuid back through said chamber outlet port;

rotary cam means in said central cavity cooperating with said pistons to produce sequential reciprocation of said pistons in said piston cylinders; and

means to axially rotate each of said pistons within said piston chambers,

the improvement in said axial rotation means including:

a foot extending radially from said piston and spaced axially from said helical groove;

a collar means positioned around each piston at said foot, each collar means having a slot engageable with said foot;

a circular ring circumscribing each of said collar means vand being engageable with each collar through gear means; and

linear'reciprocable means operably connected to said circular ring to vary the volume output capacity of said pump when said reciprocable means is moved along its linear axis, said linear, reciprocable means including a rod threadably engaging a rotatable shaft, and having a handle, said rod being reciprocated by rotation of said rotatable shaft.

2. A hydraulic pump assembly according to claim 1, wherein said circular ring has a channel in an outer cir cumferential portion thereof, and is slotted in said channel portion, said rod is positioned in said channel, and a pin on said rod is positioned in said slot.

3. A Vhydraulic pump assembly according to claim 1, wherein a control spacer is attached to said rod and said control spacer is positioned in a motion limiting cylinder, the extent of reciprocation of said rod -being limited by the extent of reciprocation of said control spacer in said motion limiting cylinder.

4. A hydraulic pump according to claim 1 wherein said rotary cam means is supported on a power shaft which is journalled in said housing on both sides of said rotary cam means.

References Cited UNITED STATES PATENTS 1,929,93 5 10/ 1933 Rennerfelt 10S-37 2,388,462 11/1945 Beeh 103-173 2,432,507 12/ 1947 Civitartese 103-17 3 FOREIGN PATENTS 571,501 9/ 1942 Great Britain. 589,942 7 1946 Great Britain. 764,143 1/ 1940 Germany. 1,045,168 3/ 1956 Germany.

WILLIAM L. FREEH, Primary Examiner U.S. Cl. X.R. 103-173 

